Process of preparing molten gelatin solution



Feb. 17, 1953 J. o. SCHERER 2,628,916

PROCESS OF PREPARING MOLTEN GELATiN SOLUTION Original Filed July 30, 1943 lNVEN'l 'OR. John Otto Scheref' MJW ATTORNEY.

Patented Feb. 17, 1953 PROCESSOF PREPARING MOLTEN GEIATIN SOLUTION John m Scherer, Detroit, Mich., assignor to R. P. Scherer Corporation, Detroit, Mich.,-a corporation of Michigan Original application July 30, '1943, Serial No. 496,817. Divided and this application April 4,

1949, Serial No. 89,738

6 Claims. (01. 106--135.)v

' This invention relates to improvements in the processof'preparing molten gelatin solutions. Itis a division of my United States application, Serial No. 496,817, filed July 30, 1943, now abandoned.

Anobi'ect' is to provide an improved process of preparing a molten gelatin solution of the desired composition and consistency and relatively free from'airbubbles.

More'parti'cularly the invention relates to the preparationof moltengelatin solutions which are relativelyviscous and which are'suitable for the casting of bandsor'ribbons such as are employed in the fabrication of hermetically sealed gelatin capsules.

A further object is to provide an improved process whereby gelatin solutions having the desired characteristics may be prepared quickly, cheaply and with the minimum of attention on thepart ofthe operator.

Ano'therobject is to provide improvements in method of preparing gelatin solutions through the employmentof whichthe operation may be carriedout with the minimum of possibility of injury to the gelatin.

Heretofore one practice of preparing a molten gelatin solution has been to soak dry gelatin flakes in a mixture of cold water and glycerin of the'proportions desired in the finished solution and thereafter to heat the soaked gelatin mass ina double boiler type of heating apparatus until the-gelatin was reduced to the molten state. The

,gelaitin was then allowed to stand for the necessary period of time for the air bubbles to pass off which time period might be 24 to 48 hours.

' Another practice'has been to soak gelatin flakes ingit masconcentrated. under carefully controlled heat and at sub-atmospheric pressure, reducing the water content to the desired amount. Careful-control of heat was necessary in this'process to prevent gelatindeterioration and though the time required was reduced, as compared with the practice first described, the concentrationstep required considerable time. Careful attention wasnecessary as ,alboiling gelatinlsolution foams quickly and violently. v It 'is'not satisfactory to mix vdrygelatin flakes withhot' waterj'for -insu .cha mixture it is difiicult to produce a smooth homogeneous solution; It is not satisfactory to fuse dry gelatin'flakes to a molten mass because of the danger'of burning the gelatin. To accomplish such 'requiresvery careful attention and a considerable length of time because of heat control required. 'Furthermore, a gelatin solution which is sufiiciently viscous for the specific purpose hereinabove mentioned is, because of such viscosity, veryslow to release contained air and'a substantial time period is required to get'the air out of the solution.

This invention is designed to'overcome the disadvantages exemplified in the two practices hereinabove discussed and to provide a gelatin solution of the required characteristics quickly and economically. I

The apparatus disclosed'in'the drawing is apparatus which has been found suitable for the carrying out of the process.

Other objects, advantages and meritorious features will more fully appearfrom the following description, appended claims and accompanying drawing wherein:

Figure 1 is a vertical section through apparatus suitable for the carrying out of the invention.

Figure 2 is a horizontal sectional view taken on the line 22 of Figure 1.

The invention is applicable to the preparation of gelatin solutions which may vary from what is known as a hard gelatin to a soft gelatin. A hard gelatin might consist of s2% dry gelatin flakes, 16% glycerin and 42% water. A soft gelatin might consist of 4 0% gelatin flakes, 3.0% glycerin and 30% water." I p r The apparatus whereby th improved process may be carried out is here illustrated slcomprising a container l0, Which has a jacketed side Wall portion I2, and a jacketed bottom wall portion M. This vessel is adapted to serveas the elatin. mel ing vessel. 'Ihe bottom walliportion is Of less di met r than the inside diameter of the side wall p rtion whereb the bottom is .supported from and communicates with the sidewall by means of short tubular sections 16 which bridge the Space between the bottom wall and the side wall and establish the fluid communication therebetween. Due to this spacing between the bottom wall and the side wall there is pr vid d a Series of discharge openings 18 for molten gelatin. The bottom wall is convex upwardly so that. as, the gelatin melts it flows down hr u h the open ngs I8.

The melting vessel .10 superposes an accumulating vessel 20 which vessel has a iacketedside wall 22 and a jacketed bottom wall 24. The jacketed side wall portion 22 communicates with the hollow bottom portion 24 as shown. These confined spaces 22 and 24 are hermetically sealed and evacuated of air to within about to mercury column of absolute vacuum. A small quantity of air free d st lled water 26 is placed in the hol ow bottom of the vessel 28. A conventional e ectric heater 28 is disposed adiacent to the jacketed bottom of the vessel 20. thermostat is indicated at 30. Connecting electric plug 32. is connected with the heater through the thermost t by lead wires 33. An insulating protective bottom wall 34 is provided as shown. At 36 is a connection whereby the jacketed portion of the vessel 20 may be'evacuated of air as hereinabove described and through which the distilled water may be placed therein.

There is indicated at 38 a valve controlled outlet through which molten gelatin may be with drawn from the vessel 21!. A flange ring 3! closes the jacketed side wall space 22 and forms a -fiange ring 42 is provided which depends below the vessel l and embraces the flange ring 3! of the vessel 20.

Upper vessel I0 is provided with a cover M adapted to be received over the open top of the vessel. A suitable gasket 46 is provided to form an air tight seal between such cover and vessel 0. 4B is a vacuum gauge for indicating the pressure within the container and 50 is an air evacuating pipe having a control valve 52. This pipe may be connected with suitable vacuum producing means to withdraw air from the container H). A glass window 54 is provided to view the operation within the container and 56 indicates a light bulb which may be connected in an electric circuit to illuminate the interior.

A valve controlled steam pipe connection 53 leads into the lower part of the jacketed side wall from one side and a valve controlled outlet pipe connection 60 leads therefrom at the opposite side. Steam may be taken in through the intake connection 58 into the jacketed portion of the vessel I 0 and steam condensate may be withdrawn through the outlet pipe 60.

I first mix the dry gelatin flakes with the desired quantity of water, and preferably plus a small excess of water over that desired in the finished solution. The water is cool water. This mixing is carried out in a suitable apparatus such as a pony mixer which thoroughly stirs the mass, sayfrom ten to thirty minutes, until the gelatin picks up the liquid and is thoroughly soaked. Gelatin solutions of the character described contain gylcerin and my liquid mixture is one of cold water and glycerin. The glycerin is provided in the proportionate amount required for the finished solution and the water is provided in approximately such amount or preferably, as above stated, slightly in excess of that required in the finished solution.

This soaked gelatin mass, with the gelatin in the solid but impregnated state, is then placed in the melting vessel ID. The discharge openings I8 are not large enough to permit the soaked gelatin flakes to fall therethrough. After the 'soaked gelatin mass has been placed in the vessel ill, the cover 44 is placed thereon and the connection 50 with a suitable conventional vac- "uum producing system, not shown, is established 1 and the valve 52 is opened so as to permit with- An electric drawal of air from the container. This evacuation of air is preferably carried down to an absolute pressure of from one-half inch to threequarter inch of mercury and is maintained for the necessary amount of time to withdraw substantially all of the air from the gelatin mass. In the practice as presently pursued a time period of about twenty minutes evacuation has been found satisfactory.

Inasmuch as the object is to get substantially all of the air out a, portion even of the water is Withdrawn, but not so as to reduce the water content below that required for the finished solution. It is for this reason that a small excess of water is originally provided. Withdrawal of water vapor flushes the air out and dilutes the small amount of air content remaining. As presently practiced, about or more of the air is evacuated.

Following this step of evacuating the air from the gelatin mass while maintaining such mass hermetically sealed against atmosphere the valve 52 is closed. Heating steam at 212 F. is then admitted through the valve controlled inlet 58 into the jacketed side wall and bottom portion of the container Ill. The gelatin mass in contact with this warm surface will melt and drain down through the openings l8 as rapidly as the same is melted and before it has been heated sufficiently long to injure the gelatin. The construction is such that the circumferential drain outlet l8 provides what might be termed a reverse funnel efiect. The surface flow area increases the further the melted gelatin flows from the center of the bottom M of vessel Ill. The purpose is to permit the molten gelatin to flow away as rapidly as it becomes molten and prevent the formation of a molten gelatin pool subjected to injurious heating. If gelatin is subjected to this heat in the melting pot for a protracted period of time it will break down and lose its Blum or jelly-like strength. Gelatin is a good heat insulator and unless the melted gelatin is withdrawn as it melts the molten gelatin pool which is formed will inhibit the melting of thesolid gelatin which superposes the liquid pool.

Disposed within the lower container 20 is an annular tapered flow directing element 62 which is shown in Fig. 1 as removably supported from the upper margin of said vessel. Such element 62 directs the molten gelatin into the vessel 20 without any appreciable splashing thereof. This draining will continue until all the gelatin within the upper vessel has been melted and drained down. i V

In the meantime the temperature of the lower vessel will be maintained at such a degree by the electric heater 28 as to maintain the gelatin in the molten state without heat injury. The thermostat may be set to maintain a temperature of F. to F. and this will cause the accumulating vessel 20 to maintain the gelatin mass at the required temperature.

When the melting vessel Ill has been emptied, as observed through the viewing window 54, then the steam supplied to the melting vessel may be cut off and the condensate valve in outlet 60 is opened and the air exhaust pipe 50 disconnected from the vacuum system. The melting tank It may then be removed from the lower vessel 20. A cover may then be placed over the lower vessel 20 and such accumulating vessel may be kept at the temperature required to maintain the molten solution in the desired state. It is obvious that the melting vessel might be kept in its superposed position if such were desired.

By melting the gelatin in this fashion it is possible to provide a molten solution which is relatively free from air bubbles and which does not require careful attention on the part of the operator during its preparation, which is constantly accumulated as formed, and which is retained at the desired temperature durin the accumulation. This process is relatively free from any possibility of damage to the gelatin during the formation of the solution. If the steam is left on too long no harm is done. Any bubbles which may have water vapor cores will be collapsed by condensation of the water vapor within them when the atmospheric pressure is restored to the gelatin solution in the accumulation vessel.

What I claim is:

1. In the process of preparing a molten gelatin solution from water-impregnated gelatin, the steps of hermetically sealing the impregnated gelatin mass from the atmosphere and withdrawing substantially all of the air therefrom, and subsequently heating the gelatin mass sufiiciently to melt the same while maintaining it hermetically sealed from the atmosphere.

2. In the process of preparing a molten gelatin solution from water-impregnated gelatin, the steps of hermetically sealing the impregnated gelatin mass from the atmosphere and withdrawing substantially all of the air therefrom, subsequently heating the gelatin mass sufficiently to melt the same while maintaining it hermetically sealed from the atmosphere, and withdrawing the melted gelatin from the mass as the same is melted.

3. In the process of preparing a molten gelatin solution from water-impregnated gelatin, the steps of hermetically sealing the impregnated gelatin mass from atmosphere and withdrawing by vacuum substantially all of the air and some of the water therefrom, closing the vacuum connection, and heating the gelatin mass to melt the same While maintaining the hermetic seal there- 4. In the process of preparing a molten gelatin solution from water-impregnated gelatin, the steps of hermetically sealing the impregnated gelatin mass from atmosphere and withdrawing by vacuum substantially all of the air and some of the water therefrom, closing the vacuum connection, heating the gelatin mass to melt the same while maintaining the hermetic seal thereon, and withdrawing the melted gelatin from the mass sufficiently rapidly to prevent the formation of a pool of melted gelatin in association with the mass.

5. In the process of preparing a molten gelatin solution from gelatin impregnated with an aqueous liquid mixture, the steps of hermetically sealing said impregnated gelatin mass against atmosphere, withdrawing by vacuum substantially all of the air from the mass, and, while maintaining the hermetic seal thereon, heating the gelatin mass throughout its bottom areato progressively melt the same, and withdrawing the melted gelatin from the mass throughout an area extending substantially ciroumferentially about and below the bottom of the mass, said withdrawal being sufilciently rapid to prevent formation of a pool of melted gelatin along the bottom of the mass.

6. That process of preparing a molten gelatin solution which comprises impregnating gelatin with water in excess of the amount desired in the molten solution, hermetically sealing the impregnated gelatin mass from the atmosphere, withdrawing by vacuum substantially all of the air and the water vapor equivalent of said excess of water from the gelatin, and, while maintaining it hermetically sealed from the air, applying heat to the gelatin sufficient to melt the same, withdrawing melted gelatin substantially as rapidly as the same in melted and depositing it within an accumulator vessel while maintaining the gelatin within said accumulator vessel in the molten state.

JOHN O'II'O SCHERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. IN THE PROCESS FOR PREPARING A MOLTEN GELATIN SOLUTION FROM WATER-IMPREGNATED GELATIN, THE STEPS OF HERMETICALLY SEALING THE IMPREGNATED GELATIN MASS FROM THE ATMOSPHERE AND WITHDRAWING SUBSTANTIALLY ALL OF THE AIR THEREFROM, AND SUBSEQUENTLY HEATING THE GELATIN MASS SUFFICIENTLY TO MELT THE SAME WHILE MAINTAINING IT HERMETICALLY SEALED FROM THE ATMOSPHERE. 